KR20230090327A - Manufacturing method of styrene-butadiene rubber containing recycled rubber powder - Google Patents

Abstract

A method for producing styrene-butadiene rubber containing micronized recycled rubber powder, the method comprising:
(a) preparing a suspension comprising micronized recycled rubber powder, water and at least one surfactant;
(b) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex to obtain a styrene-butadiene latex containing micronized recycled rubber powder;
(c) adding the latex obtained in step (b) to coagulation to obtain coagulated styrene-butadiene rubber containing micronized recycled rubber powder;
includes;
here:
- in step (a), the particle size of the micronized recycled rubber powder is in the range of 0.05 mm to 0.8 mm, preferably in the range of 0.1 mm to 0.4 mm;
- In step (a), the at least one surfactant is present in an amount ranging from 0.5% to 3% by weight, preferably from 1% to 2.5% by weight, based on the total weight of the micronized recycled rubber powder. do;
- In the step (a), the micronized recycled rubber powder has a concentration in water ranging from 1% to 50% by weight, preferably from 5% to 30% by weight, based on the total weight of the water.
The micronized recycled rubber powder obtained from the above-mentioned method is useful in a vulcanizable elastomer composition as such or as a mixture with, for example, natural rubber (NR), polybutadiene (BR), styrene-butadiene copolymer or mixtures thereof. In turn, the vulcanizable elastomer composition can be used in various fields such as, for example, tires, shoe soles, brakes, and conveyor belts.

Description

Manufacturing method of styrene-butadiene rubber containing recycled rubber powder

The present invention relates to a method for producing styrene-butadiene rubber containing micronized recycled rubber powder.

More particularly, the present invention relates to a process for producing styrene-butadiene rubber comprising micronized recycled rubber powder, comprising the steps of: (a) comprising micronized recycled rubber powder, water and at least one surfactant; preparing a suspension; (b) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex to obtain a styrene-butadiene latex containing micronized recycled rubber powder; (c) adding the latex obtained in step (b) to coagulation to obtain coagulated styrene-butadiene rubber containing micronized recycled rubber powder.

Styrene-butadiene comprising the micronized recycled rubber powder obtained from the above method as such or in a mixture with other rubbers such as, for example, natural rubber (NR), polybutadiene (BR), styrene-butadiene copolymers or mixtures thereof Rubber can advantageously be used in vulcanizable elastomer compositions, which in turn can be used in various fields such as, for example, tires, shoe soles, brakes, and conveyor belts.

Rubber recycling is a constantly evolving field that is attracting increasing attention due to growing interest in issues such as, for example, environmental sustainability and the circular economy. Consequently, there are numerous scientific articles and patents on this recycling.

One of the most widely used methods for the purpose of recycling rubber is to reduce it to a fine powder and add it to virgin rubber via dry mechanical mixing.

For example, U.S. Patent 9,840,613 relates to a polymeric formulation useful as a structural material for making a wide variety of articles, the polymeric formulation consisting of: (1) about 45% to about 85% by weight micronized rubber. A powder, (2) from about 15% to about 45% by weight of a metallocene polyolefin elastomer, and (3) from about 1% to about 10% by weight of polyethylene grafted with maleic anhydride. The ingredients of the polymer formulation mentioned above are dried and mixed in a twin screw extruder.

It is also known to recycle rubber by a technique known as devulcanization which aims to break the sulfur bridges in order to bring the polymer as close as possible to its original shape.

For example, U.S. Patent 5,602,586 relates to a method for devulcanizing vulcanized rubber by devulcanization, the method comprising the following steps: contacting crumbs of vulcanized rubber with a solvent and an alkali metal to form a reaction mixture obtaining; heating the reaction mixture while stirring in the absence of oxygen to a temperature sufficient to react the alkali metal with the sulfur present in the vulcanized rubber; and maintaining the temperature below the temperature at which thermal cracking of the rubber occurs to obtain desulfurization.

Further details of desulphurization technology can be found, for example, in patents US 6,541,526 and US 9,527,978.

Rubber recycling processes involving the use of rubber in emulsion or solution are also known.

For example, Chinese patent application CN 101792546 relates to a method for preparing a rubber powder and a composition composed of rubber, the method comprising the following steps: rubber powder is mixed with rubber in an emulsion or solution state or in a solid form that has not been previously dried. of wet rubber to obtain an intermediate product consisting of a rubber-rubber powder composition, wherein the rubber powder is optionally a material containing a powder additive or a sizing agent containing water or a softening oil ( optionally) containing, and subsequently performing a liquid removal treatment to obtain a product consisting of a rubber-rubber powder composition in a solid state.

Chinese patent application CN 102344591 relates to a process for preparing a composition comprising rubber, characterized in that it comprises the following steps: (1) in a closed mixer, from 90 mesh (approximately 0.16 mm) to 200 mesh (0.074 mm) of graded or mixed particle size recycled rubber powder is mixed with emulsion or solution rubber to obtain a homogeneous material, wherein the recycled rubber contains powder additives, or water and/or softening oil. Optionally containing an additive to do, step; or in a kneading machine, mixing the recycled rubber powder with wet rubber in solid form that has not been dried beforehand to obtain a homogeneous material; (2) The homogeneous material obtained in step (1) above is subjected to, for example, de-emulsification, centrifugation, pelletisation, hot air fluidization, flue gas baking, vaporization in a steam cylinder , hot extrusion, dewatering treatment by traditional liquid removal techniques, to obtain a homogeneous composition comprising rubber-rubber powder.

However, the method may have some drawbacks, for example:

- deterioration of the physical-mechanical properties of the elastomeric composition when it is used;

- problems related to handling as well as health of workers;

- Technical problems related to contamination of manufacturing lines and equipment used.

Micronized recycled rubber powder is known to be very hygroscopic. Moisture absorption by the micronized recycled rubber powder can deteriorate both the mechanical mixing with the raw rubber ("dry mixing") and the subsequent vulcanization process, leading to deterioration in the physical and mechanical properties of the final vulcanized product.

In addition, the use of micronized recycled rubber powder in mechanical mixing ("dry mixing") is an aspect of both environmental sustainability and worker health, for example to avoid hazards such as explosion or dispersal of fine particles into the atmosphere. requires careful management, resulting in increased process costs. Additionally, the use of micronized recycled rubber powder in mechanical mixing ("dry mixing") can be a major problem for improperly equipped facilities.

Finally, the use of micronized recycled rubber powder can lead to contamination of manufacturing lines and equipment used, which can lead to clogging and malfunctions, increasing both time and process costs.

Therefore, the present applicant has raised the problem of finding a method for producing styrene-butadiene rubber containing micronized recycled rubber powder, which can overcome the above problems.

At present the Applicant has found a micronization, which, thanks to the use of a suspension comprising micronized recycled rubber powder having a specific size, water and at least one surfactant present in a specific amount, makes it possible to overcome the above-mentioned drawbacks. A novel process for the production of styrene-butadiene rubber comprising recycled rubber powder has been discovered. The method is a vulcanizable elastomeric composition (which in turn is, for example, a tire , shoe soles, brakes, and conveyor belts), which can be advantageously used in various fields).

Accordingly, an object of the present invention is a method for producing styrene-butadiene rubber containing micronized recycled rubber powder, the method comprising:

(a) preparing a suspension comprising micronized recycled rubber powder, water and at least one surfactant;

(b) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex to obtain a styrene-butadiene latex containing micronized recycled rubber powder;

(c) adding the latex obtained in step (b) to coagulation to obtain coagulated styrene-butadiene rubber containing micronized recycled rubber powder;

includes;

here:

- in step (a), the particle size of the micronized recycled rubber powder is in the range of 0.05 mm to 0.8 mm, preferably in the range of 0.1 mm to 0.4 mm;

- In step (a), the at least one surfactant is present in an amount ranging from 0.5% to 3% by weight, preferably from 1% to 2.5% by weight, based on the total weight of the micronized recycled rubber powder. do;

- In the step (a), the micronized recycled rubber powder has a concentration in water ranging from 1% to 50% by weight, preferably from 5% to 30% by weight, based on the total weight of the water.

For the purposes of this description and the claims below, the definition of a numerical interval always includes the extreme values unless otherwise specified.

For the purposes of this description and the claims below, the term “comprising” also includes the terms “consisting essentially of” or “consisting of”.

For the purposes of this description and the claims below, the particle size of the micronized recycled rubber powder was determined according to standard ASTM D5644-18.

For the purpose of the method object of the present invention, the micronized recycled rubber powder is, for example, whole end-of-life tires (ELT) or tire parts (eg treads) and may originate from different types of rubber products, such as Therefore, the micronized recycled rubber powder can contain different types of rubber, such as natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), as well as, for example, carbon black, silica, sulfur and accelerators. , fillers such as additives of various kinds.

Micronized recycled rubber powder can be obtained by processes known in the art. For example, micronized recycled rubber powder can be obtained through a cryogenic process, a mechanical crushing process, or a high-pressure process in the presence of water. In all processes, the steel component is removed by a magnetic separator and the fiber component is separated by an air classifier or other separation equipment. In the cryogenic process, ground rubber is frozen at cryogenic temperatures and then ground into small particles. Mechanical crushing processes, which are generally carried out at room temperature (25° C.), use various crushing equipment, for example cracker mills, granulators, etc., to mechanically break rubber into small particles. The high-pressure procedure in the presence of water involves subjecting a rubber product, such as a waste tire, to a high-pressure water jet that scrapes the outermost portion of the waste tire to create small particles.

For the purposes of the present invention, micronized recycled rubber powder obtained by any one of the processes known in the art, for example obtained by any of the above processes, may be used.

Examples of currently commercially available micronized recycled rubber powders that can advantageously be used for the purposes of the present invention are PolyDyne ^™ from Lehigh Technologies (d ₉₀ ranging from 0.074 mm to 0.4 mm) under the tradename, rubber powders from Albatros B.0/0.35 (d ₉₀ < 0.35 mm), a product known by TyreXol ^™ CWN 0-400 (d ₉₀ < 0.33 mm) from Tyre Recicling Solutions.

According to a preferred embodiment of the present invention, in step (a), said at least one surfactant is, for example, a nonionic surfactant, such as for example polyoxyethylene derivatives of fatty acids, alkyl-polyglucosides, ethanolamides. , ethoxylated amides, ethoxylated amines, ethoxylated acids, polyoxyethylene alkyl-ethers or mixtures thereof.

According to a further preferred embodiment of the present invention, in step (a), said at least one surfactant is, for example, an anionic surfactant, such as, for example, by a long carbon atom chain terminated by a carboxylate or sulfonate group. Formed salts [eg, sodium lauryl sulfate (SLS), sodium lauryl ethoxy sulfate (SLES)], alkyl-benzene-sulfonic acids (ABS), polysulfonated aromatic ethers (eg, Dow Chemical by Dowfax ^™ 2A1) or mixtures thereof; saturated or unsaturated fatty acids containing 6 to 22 carbon atoms in the molecule, such as for example sodium of caproic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid or mixtures thereof; potassium, lithium or ammonium salts, preferably sodium or potassium, or mixtures of said salts; Dimerization, disproportionation of resinous acid mixtures containing abietic acid, neoabietic acid, palustric acid, levopimaric acid or mixtures thereof; A sodium, potassium, lithium or ammonium salt, preferably sodium or potassium, of a modified resinous acid obtained by hydrogenation, modification, or a mixture of said salts [e.g. disproportionate of resinous potassium soap 80% Gresinox 578 M from Parchem potassium salts derived from chemotherapy].

According to a further preferred embodiment of the present invention, in step (a), said at least one surfactant is, for example, a cationic surfactant, such as for example a long-chain quaternary ammonium salt [e.g. benzalkonium chloride (benzalkonium chloride (BAC)), cetyl-trimethylammonium bromide (CTAB), hexadecyltrimethylammonium bromide] or mixtures thereof.

According to a further preferred embodiment of the invention, in step (a), said at least one surfactant is, for example, an amphoteric surfactant, such as for example coco-amidopropyl-betaine, dodecyl-betaine , lecithin, aminocarboxylic acids, or mixtures thereof.

According to a preferred embodiment of the present invention, step (a) is performed for a variable time depending on the size of the mixer and sufficient to obtain a homogeneous suspension, preferably in the range of 2 to 60 minutes, preferably in the range of 4 to 40 minutes. It may be carried out at a temperature in the range of 20 ° C to 90 ° C, preferably 50 ° C to 80 ° C for a time of.

The step (a) is carried out in a mixer provided with a stirring system suitable for obtaining a homogeneous suspension, i.e. a suspension in which the micronized recycled rubber powder is homogeneously distributed throughout the entire volume of water and surfactant, the micronized recycled rubber powder, water and at least one surfactant. Preferably, the agitation system is a mixed secondary flow impeller, such as, for example, a 45° "Pitch Blade" type impeller, or, such as, for example, Lightnin's A310 3-blade propeller. It may consist of a purely axial flow “hydrofoil” type impeller.

It should be noted that by operating as described above, a stable homogenous ("turbid") suspension is obtained at the end of step (a). For purposes of this description, the term “stable homogeneous suspension” means that such a suspension exhibits no visible stratification, phase separation or sedimentation at room temperature (25° C.) in the absence of agitation for at least 5 minutes. it means.

For the purposes of the subject matter of the present invention, the styrene-butadiene latex used is prepared by processes known in the art, for example patents US 4,070,324 and US 5,504,168, or those described in El-Aasser MS and Sudol D., " Emulsion Polymerization and Emulsion Polymers "(1997), Klein A. and Daniel ES Ed., John Wiley and Sons, New York, Chapter VI, pages 37-55].

According to a preferred embodiment of the present invention, in the step (b), the at least one styrene-butadiene latex is in the range of 10% to 50% by weight, preferably 15% to 30% by weight based on the total weight of the latex % of styrene-butadiene polymer and an amount of linked styrene in the range of 10% to 60% by weight, preferably in the range of 20% to 50% by weight relative to the total weight of the latex.

According to a preferred embodiment of the present invention, in the step (b), the suspension obtained in the step (a) is in the range of 5% to 95% by weight based on the total weight of the styrene-butadiene rubber contained in the latex, preferably may be added in an amount to have an amount of micronized recycled rubber powder ranging from 8% to 35% by weight.

The step (b) may be carried out in a mixer (referred to as "pre-mixer") provided with a stirring system suitable for obtaining a styrene-butadiene latex containing micronized recycled rubber powder, wherein the micronized recycled rubber powder is is evenly distributed in Preferably, the agitation system is a mixed secondary flow impeller, such as, for example, a 45° "pitch blade" type impeller, or a pure axial flow "hydrofoil" type, such as, for example, Lightnin's A310 3-blade propeller. It may consist of an impeller.

According to one embodiment of the present invention, the step (b) is in the range of 20 ℃ to 90 ℃ for a variable time depending on the size of the mixer and sufficient to obtain a styrene-butadiene latex containing micronized recycled rubber powder, preferably preferably in a mixer (referred to as a pre-mixer) at a temperature in the range of 50° C. to 80° C., wherein the powder is preferably mixed for a period of time ranging from 1 minute to 45 minutes, preferably ranging from 5 minutes to 15 minutes. homogeneously distributed in the latex.

In the mixer (referred to as the pre-mixer), additional components commonly used in emulsion radical copolymerization processes for the production of styrene-butadiene rubber (e-SBR), such as, for example, surfactants selected from those reported above, Extender oil, antioxidants may be added: More details regarding the emulsion radical copolymerization process for the production of styrene-butadiene rubber (e-SBR) can be found in, for example, patents US 4,070,324 and US 5,504,168 or the above Reported literature [El-Aasser MS and Sudol D. in " Emulsion Polymerization and Emulsion Polymers " (1997), Lovell P. A and El-Aasser Ed., John Wiley and Sons, New York, Chapter VI, pages 208-234 ] can be found in

Alternatively, step (b) may be carried out in the same coagulation mixer (referred to as "coagulation tank") in which step (c) (coagulation) is carried out: in this case, the suspension obtained in step (a) and Mixing between the styrene-butadiene latex takes place directly in the coagulation mixer (referred to as "coagulation tank") [step (c1)].

Accordingly, a further object of the present invention is to:

(a1) preparing a suspension comprising micronized recycled rubber powder, water and at least one surfactant;

(c1) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex and subjecting the whole to coagulation to obtain a coagulated styrene-butadiene rubber containing micronized recycled rubber powder;

A method comprising;

here:

- in step (a1), the particle size of the micronized recycled rubber powder is in the range of 0.05 mm to 0.8 mm, preferably in the range of 0.1 mm to 0.4 mm;

- In step (a1), the at least one surfactant is present in an amount ranging from 0.5% to 3% by weight, preferably from 1% to 2.5% by weight, based on the total weight of the micronized recycled rubber powder. do;

- In the step (a1), the micronized recycled rubber powder has a concentration in water ranging from 1% to 50% by weight, preferably from 5% to 30% by weight, based on the total weight of the water.

When the step (b) is carried out in the same coagulation mixer (referred to as "coagulation tank") in which the step (c) (coagulation) is carried out, i.e. in the case of [step (c1)], the mixer ("pre-mixer" In order to obtain a styrene-butadiene latex in which the above-reported additional component is homogeneously distributed in the latex by operation under the same conditions as described above for step (b), the above-reported additional component and styrene-butadiene It should be noted that mixing between latexes can still be performed.

The step (a1) is carried out under the same conditions as described above for step (a).

According to a preferred embodiment of the present invention, in the step (c1), the at least one styrene-butadiene latex is in the range of 10% to 50% by weight, preferably 15% to 30% by weight, based on the total weight of the latex. % of styrene-butadiene polymer, and an amount of linked styrene in the range of 10% to 60% by weight, preferably in the range of 20% to 50% by weight relative to the total weight of the latex.

According to a preferred embodiment of the present invention, in the step (c1), the suspension obtained in the step (a1) is in the range of 5% to 95% by weight based on the total weight of the styrene-butadiene rubber contained in the latex, preferably may be added in an amount to have an amount of micronized recycled rubber powder ranging from 8% to 35% by weight.

According to a preferred embodiment of the present invention, step (c) and step (c1) are, for example, an alkylamine-epicloridine copolymer (eg dimethylamine known by the trade name Floquat® FL 2250 from NSF -epichlorohydrin copolymer).

The amount of coagulant and other components that may be present, such as, for example, surfactants, extender oils, antioxidants, depends on the amount of latex and micronized recycled rubber powder used.

According to a preferred embodiment of the present invention, steps (c) and (c1) are based on the size of the coagulation mixer (referred to as "coagulation tank"), the suspension obtained in step (a) or step (a1) and the styrene used - 40° C. to 90° C. for a time variable depending on the amount of butadiene latex, temperature and pH, the stirring system used, preferably in the range of 5 minutes to 120 minutes, preferably in the range of 10 minutes to 60 minutes, preferably Preferably it can be carried out at a temperature in the range of 60 ℃ to 80 ℃.

According to a preferred embodiment of the present invention, steps (c) and (c1) may be performed at a pH of 5 or less, preferably in the range of 2.5 to 4.

According to a preferred embodiment of the present invention, at least one inorganic acid, such as for example sulfuric acid, phosphoric acid, preferably sulfuric acid, may be added in step (c) and step (c1).

According to a preferred embodiment of the present invention, the at least one organic acid may be added in an amount to maintain the pH at 5 or less, preferably in the range of 2.5 to 4 during the entire period of steps (c) and (c1). there is.

Steps (c) and (c1) above may be carried out in a coagulation mixer (referred to as "coagulation tank") provided with an agitation system. The agitation system also, when the step (b) is carried out in the same coagulation mixer (referred to as "coagulation tank") as in the step (c) [step (c1)], micronized recycled rubber in styrene-butadiene latex It should be noted that it is suitable for allowing a homogeneous distribution of the powder. Preferably, the agitation system is a mixed secondary flow impeller, eg a 45° "pitch blade" type impeller, or a pure axial flow "hydrofoil" type impeller, eg Lightnin's A310 3-blade. can be made with

After solidification, the styrene-butadiene rubber containing micronized recycled rubber powder is generally present in the form of crumbs.

Preferably, the crumb is neutralized by adding an aqueous solution containing at least one organic base, for example sodium carbonate solution, followed by washing with water. The water used for the washing may be both deionized and non-deionized water.

Preferably, washing with water may be carried out at a temperature ranging from 35 °C to 90 °C, preferably from 40 °C to 90 °C.

The styrene-butadiene rubber comprising micronized recycled rubber powder may be subjected to one or more washings with water, for example from one to seven times, which may be carried out in batches or continuously, preferably continuously. there is. Partial drying of the styrene-butadiene rubber comprising micronized recycled rubber powder may also be carried out between washings.

After washing with water, the styrene-butadiene rubber containing micronized recycled rubber powder is usually subjected to water removal ("dewatering"). Water removal involves first subjecting styrene-butadiene rubber, including micronized recycled rubber powder, to mechanical treatment, for example by means of a screw device, and then subjecting it to evaporation, for example by means of a stove, hot plate. in two steps by adding; or by directly subjecting the styrene-butadiene rubber containing micronized recycled rubber powder to evaporation, for example by a stove or hot plate, in a single step. The water removal ("dehydration") may be carried out at a temperature in the range of 40°C to 150°C, preferably in the range of 60°C to 120°C for a time greater than 5 minutes, preferably in the range of 8 to 45 minutes; , the time should be sufficient to obtain a styrene-butadiene rubber comprising micronized recycled rubber powder having a residual moisture content of less than 1% by weight of the total weight of the styrene-butadiene rubber.

According to a preferred embodiment of the invention, the process can be carried out continuously, preferably continuously, as well as "batchwise".

As mentioned above, the styrene-butadiene rubber comprising the micronized recycled rubber powder obtained from the above method may be used as is or with, for example, natural rubber (NR), polybutadiene (BR), styrene-butadiene copolymer or mixtures thereof. It can be advantageously used in a vulcanizable elastomer composition in a mixture with other rubbers, such as the vulcanizable elastomer composition, which in turn can be used in various fields such as, for example, tires, shoe soles, brakes, and conveyor belts.

For example, the styrene-butadiene rubber comprising the micronized recycled rubber powder may be used in a mixture with carbon black and/or silica in a vulcanizable elastomer composition suitable for manufacturing a tire.

Accordingly, a further subject of the present invention is at least one styrene-butadiene rubber comprising the micronized recycled rubber powder obtained as described above, at least one filler selected from carbon black, silica or mixtures thereof and at least one vulcanizing agent It is a vulcanizable elastomer composition comprising a. Preferably, the filler may be present in the vulcanizable elastomer composition in an amount ranging from 5 phr to 500 phr.

The vulcanizable elastomer composition may include, in addition to the styrene-butadiene rubber containing the micronized recycled rubber powder, other elastomers such as natural rubber (NR), polybutadiene (BR) or mixtures thereof. .

For purposes of this invention and the claims that follow, the term "phr" refers to the weight of a given component per 100 parts by weight of styrene-butadiene rubber, including micronized recycled rubber powder and optionally other elastomers present in the vulcanizable elastomer composition. means wealth.

The vulcanizing agent may be selected, for example, from soluble or insoluble elemental sulfur, or a sulfur donor, or mixtures thereof.

Sulfur donors are, for example, dimorpholyl disulfide (DTDM), 2-morpholino-dithiobenzothiazole (MBSS), caprolactam disulfide, dipentamethylenethiuram tetrasulfide (DPTT), tetramethyl thiuram disulfide (TMTD) or mixtures thereof.

If the vulcanizing agent is selected from sulfur or sulfur donors, to increase the vulcanization yield, for example dithiocarbamates, thiurams, thiazoles, sulfenamides, xantogenates, guanidine derivatives, caprolactam, thiourea derivatives or It may also be advantageous to use other additives (eg accelerators) such as mixtures thereof.

In the vulcanizable elastomer composition, the sulfur, and/or the sulfur donor, and the other additives mentioned above optionally present are generally present in an amount ranging from 0.05 phr to 10 phr, preferably from 0.1 phr to 8 phr. do.

Other ingredients may be added to the vulcanizable elastomer composition of the present invention.

For example, inorganic or organic compounds may be added. Examples of such compounds include zinc oxide; zinc carbonate; lead oxide; saturated or unsaturated organic fatty acids or zinc salts thereof; polyalcohol; amino alcohols (eg triethanolamine); amines (eg, dibutylamine, dicyclohexylamine, cyclohexylethylamine); polyether amines; or a mixture thereof.

Vulcanization such as for example N-cyclohexyl-thiophthalimide (PVI), N,N'-dinitrosopentamethylene-tetramine (DNPT), phthalic anhydride (PTA), diphenylnitrosamine or mixtures thereof Inhibitors may also be added.

In addition to the above-mentioned vulcanizing agents and/or other compounds, subject vulcanizable elastomer compositions of the present invention are other additional additives conventionally used in elastomeric compositions and known to those skilled in the art, such as, for example, other fillers, fillers activators, ozone protectants, aging inhibitors, antioxidants, processing aids, extender oils, plasticizers, reinforcing materials, release agents.

Other fillers which can be used for the purposes of the present invention are, for example, barium sulfate, titanium dioxide, zinc oxide, calcium oxide, calcium carbonate, magnesium oxide, aluminum oxide, iron oxide, aluminum hydroxide, magnesium hydroxide, aluminum silicate, diatomaceous earth, talc, kaolin, bentonite, carbon nanotubes, Teflon® (preferably in powder form), silicates or mixtures thereof. However, the total amount of filler is in the range of 5 phr to 500 phr.

Filler activators which can be used for the purposes of the present invention are, for example, organic silanes such as, for example, bis(triethoxysilylpropyl)polysulfide, vinyltrimethylsilane, vinyl-dimethoxymethylsilane, vinyltrie Toxysilane, Vinyltris-(2-methoxyethoxy)silane, N-cyclohexyl-3-aminopropyl-trimethoxysilane, 3-amino-propyltrimethoxysilane Methyltrimethoxysilane, methyltriethoxy silane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, isooctyltrimethoxysilane, isooctyltriethoxysilane, hexadecyltrimethoxysilane, (octadecyl)methyl-dimethoxysilane or mixtures thereof. . Additional filler activators are, for example, surfactants such as triethanolamine, ethylene glycol or mixtures thereof. The amount of filler activator is generally in the range of 0 phr to 10 phr.

A further subject of the invention is a vulcanized product obtained from vulcanization of said vulcanizable elastomer composition.

The present invention will now be illustrated in more detail through an embodiment with reference to FIGS. 1 and 2 reported below.

1 schematically illustrates a first embodiment of the method subject of the invention. For this purpose, micronized recycled rubber powder (micronized powder), water and at least one surfactant (e.g. Potassium Soap 80% Gresinox 578 M) are mixed with a stirring system (e.g. a 45° "pitch blade"). A suspension ("turbid") was obtained [step (a)]. The suspension obtained in step (a) (“turbidity”) is mixed with a second mixer 2 equipped with a stirring system (e.g. 45° “pitch blade” type impeller or 3-blade propeller A310 from Lightnin) ( referred to as "pre-mixer"), where styrene-butadiene latex (SBR latex) and any other ingredients [e.g., surfactant, extender oil, antioxidant (other ingredients)] are also fed to finely Styrene-butadiene latex containing recycled rubber powder was obtained [(step (b)] (SBR latex + micronized powder). The obtained latex was mixed with a stirring system (for example, a 45 ° "pitch blade" type impeller or Lightnin 3-blade propeller A310 from ) to a third mixer (eg coagulation mixer referred to as "coagulation tank"), into which acid (eg sulfuric acid) and coagulant (eg Floquat FL 2250) was also supplied, subjected to coagulation [step (c)], pH neutralization (eg using an aqueous solution of sodium carbonate), washing with water and removal of water ("dehydration"), to obtain micronized recycled rubber powder A styrene-butadiene rubber containing (eSBR rubber + micronized powder) was obtained.
2 schematically illustrates a second embodiment of the method subject of the invention. For this purpose, micronized recycled rubber powder (micronized powder), water and at least one surfactant (e.g. Potassium Soap 80% Gresinox 578 M) are mixed with a stirring system (e.g. a 45° "pitch blade"). to a first mixer 1 equipped with an impeller of this type or a 3-blade propeller A310 from Lightnin) to obtain a suspension ("turbidity") [step (a1)]. In a second mixer 2 (referred to as “pre-mixer”) equipped with an agitation system (e.g. a 45° “pitch blade” type impeller or a 3-blade propeller A310 from Lightnin), styrene-butadiene latex (SBR latex) and optional other components [(eg, surfactant, extender oil, antioxidant (additional component)] were supplied to obtain a styrene-butadiene latex (SBR + additional component) containing the above other components The obtained latex is mixed with a third mixer (i.e. a third mixer (i.e. a "coagulation tank") equipped with an agitation system (e.g. a 45° "pitch blade" type impeller or a 3-blade propeller A310 from Lightnin). (3)), and to the suspension obtained in step (a1) (“turbidity”), an acid (eg sulfuric acid) and a coagulant (eg Floquat FL 2250) are also fed. and the whole was subjected to coagulation [step (c1)], pH neutralization (using, for example, an aqueous solution of sodium carbonate), washing with water and removal of water ("dehydration") to obtain a styrene-containing micronized recycled rubber powder. Butadiene rubber (eSBR rubber + micronized powder) was obtained.
In order to better understand and practice the present invention, some illustrative and non-limiting examples thereof are reported below.

Example 1

In a first 20 liter mixer equipped with a stirring system consisting of an impeller of the 45° “pitch blade” type, 67.5 g of micronized recycled rubber powder originating from waste tires (ELT) [rubber powder B.0/0.35 (d ₉₀ < 0.35 mm) - Albatros], 675 ml of water and 13.5 g of a 10% by weight aqueous solution of an anionic surfactant (potassium soap 80% Gresinox 578M - Parchem) were loaded: the whole was stirred at 310 rpm for 5 minutes at 60 ° C. On hold, 765 g of suspension (“turbid”) were obtained.

The suspension ("turbidity") was sent to a second 20 liter mixer (referred to as "premixer") equipped with a stirring system consisting of a 45° "pitch blade" type impeller, where 3.2 liters of styrene-butadiene latex ( 21% by weight of styrene-butadiene polymer and 40% by weight of styrene, relative to the total weight of the latex), 2.7 g of antioxidant (Irganox® 1520L - Basf), 252 g of aromatic oil [RAE ("residual aromatic extract ") - Clematis RL - Eni) and 25 g of a 10% by weight aqueous solution of an anionic surfactant (potassium soap 80% Gresinox 578 M - Parchem) were loaded: the whole was kept under stirring at 310 rpm for 10 minutes at 60°C , to obtain 4.25 liters of styrene-butadiene latex containing micronized recycled rubber powder.

A third 70 liter mixer equipped with an agitation system consisting of a 45° “pitch blade” type impeller (i.e. a solidification mixer referred to as “coagulation tank”) was loaded with 10 liters of deionized water and brought to a temperature of 70° C. Afterwards, sulfuric acid (Aldrich) was gradually fed until reaching a pH value of 3: Subsequently, at a flow rate of about 0.7 liter/min, styrene-butadiene latex containing the micronized recycled rubber powder obtained as reported above 4.25 liters and 13.4 grams of coagulant (Floquat FL 2250 - SNF) were loaded. At the end, the whole was kept under stirring at 100 rpm for an additional 30 minutes at a temperature of 70° C. and pH 3: during coagulation, it was necessary to add sulfuric acid (Aldrich) again to maintain pH 3. Subsequently, while still stirring, at 100 rpm, the temperature was brought to 80° C., then sodium carbonate (Aldrich) was added to bring the pH to a value of 6.5 to 7: when the desired pH was reached, micronized recycled rubber The coagulated latex was filtered to recover styrene-butadiene rubber crumb containing powder, which was then washed under a flow of deionized water at a temperature of about 70° C. for 10 minutes.

After 10 minutes, the styrene-butadiene rubber crumbs containing micronized recycled rubber powder were dried at 100° C. in an air oven for 24 hours (residual moisture: less than 1%).

Example 2

Example 2 was run under the same operating conditions as Example 1 using different amounts of components: Table 1 below shows the amounts of various components for the production of styrene-butadiene rubber comprising micronized recycled rubber powder. .

Suspension preparation ("turbidity")
(first mixer) ingredient sheep water 1.35 liters Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 27 grams ELT rubber powder B.0/0.35 (d ₉₀ < 0.35 mm) 135 grams 2nd Mixer
("Premixer") ingredient sheep Styrene-Butadiene Latex 3.2 liters RAE ("residual aromatic extract") - Clematis RL 252 grams Irganox® 1520L 2.7 grams Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 25 grams Suspension ("turbidity") 1512 grams 3rd Mixer
("coagulation tank") ingredient sheep water 10 liters Latex from premixer 4.99 liters Floquat FL 2250 13.4g sulfuric acid q.s.* sodium carbonate q.s.*

*: As much as enough.

Example 3

Example 3 was run under the same operating conditions as Example 1 using different amounts of components and a different aromatic oil [TDAE ("Treated Distilled Aromatic Extract") - Norman 346 -ORGKHIM]: It shows the amount of various components for the production of styrene-butadiene rubber containing recycled rubber powder.

Suspension preparation ("turbidity")
(first mixer) ingredient sheep water 1.35 liters Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 27 grams ELT rubber powder B.0/0.35 (d ₉₀ < 0.35mm) 135 grams 2nd Mixer
("Premixer") ingredient sheep SBR Latex 3.2 liters TDAE ("Treated Distilled Aromatic Extract") - Norman 346 252 grams Irganox® 1520L 2.7 grams Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 25 grams Suspension ("turbidity") 1512 grams 3rd Mixer
("coagulation tank") ingredient sheep water 10 liters Latex from premixer 4.99 liters Floquat FL 2250 13.4g sulfuric acid q.s.* sodium carbonate q.s.*

*: As much as enough.

Example 4

Example 4 is the same as Example 1, using different amounts of components, a different styrene-butadiene latex (the amount of styrene-butadiene polymer is 21% by weight and the amount of styrene is 23.5% by weight relative to the total weight of the latex) and without aromatic oil. The operation was carried out under operating conditions: Table 3 below shows the amounts of various components for the production of styrene-butadiene rubber comprising micronized recycled rubber powder.

Suspension preparation ("turbidity")
(first mixer) ingredient sheep water 1.35 liters Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 27 grams ELT rubber powder B.0/0.35 (d ₉₀ < 0.35mm) 135 grams 2nd Mixer
("Premixer") ingredient sheep SBR Latex 3.2 liters Irganox® 1520L 2.7 grams Potassium Soap 80% Gresinox 578 M
(10% by weight aqueous solution) 25 grams Suspension ("turbidity") 1512 grams 3rd Mixer
("coagulation tank") ingredient sheep water 10 liters Latex from premixer 4.99 liters Floquat FL 2250 13.4g sulfuric acid q.s.* sodium carbonate q.s.*

*: As much as enough.

Example 5

A tread compound was prepared using styrene-butadiene rubber containing the micronized recycled rubber powder obtained in Examples 1 and 2 reported above.

The compound comprising the styrene-butadiene rubber comprising the micronized recycled rubber powder obtained in Example 1 is hereinafter referred to as (A).

The compound comprising the styrene-butadiene rubber comprising the micronized recycled rubber powder obtained in Example 2 is hereinafter referred to as (B).

The physical and mechanical properties of this compound were compared with those of two other compounds defined as follows.

(C) Micronized recycled rubber powder derived from styrene-butadiene rubber (Europrene ^® 1739 - Versalis) and waste tires (ELT) added by dry mixing [rubber powder B.0/0.35 (d ₉₀ < 0.35 mm) - Albatros] (10 phr);

(D) styrene-butadiene rubber (Europrene ^® 1739 - Versalis) and micronized recycled rubber powder derived from waste tires (ELT) added by dry mixing [rubber powder B.0/0.35 (d ₉₀ < 0.35 mm) - Albatros] (20 phr).

preparation of compounds

The compounds were prepared in a 1.6 liter Banbury type internal mixer: the operating conditions are reported in Table 4 below and the ingredients and amounts are given in Table 5 below.

Banbury supply hour
(minute) Operating conditions Banbury
60 rpm; FF*: 0.70; Temperature: 60℃ Compounds (A) and (B) Compounds (C) and (D) 0 Styrene-butadiene rubber + ELT
(Obtained from Example 1 and Example 2) ^Europrene® 1739 One 1/2 carbon black + oil + other ingredients reported in Table 5 (except sulfur, TBBS and TBDT 80) 1/2 carbon black + ELT + oil + other ingredients reported in Table 5 (except sulfur, TBBS and TBDT 80) 3 1/2 carbon black 1/2 carbon black 6 dispose
( _Tmax 140℃) dispose
( _Tmax 140℃) Promotion hour
(minute) Operating conditions Banbury
60 rpm; FF*: 0.70; Temperature: 60℃ 0 Released compounds + sulfur + TBBS and TBDT 80 Released compounds + sulfur + TBBS and TBDT 80 2 dispose
( _Tmax 105℃) dispose
( _Tmax 105℃)

*FF: Filling factor.

The sample was then vulcanized at 160° C. according to the ISO 6502-1:2018 standard.

ingredient compound A
(phr) compound B
(phr) compound C
(phr) compound D
(phr) e-SBR + micronized powder 147.5
157.5 - - ^Europrene® 1739 - - 137.5 137.5 ELT - - 10 20 N220 80 80 80 80 aromatic oil 10 10 10 10 WB220 2 2 2 2 6-PPD 0.8 0.8 0.8 0.8 stearic acid 2.0 2.0 2.0 2.0 TMQ 0.6 0.6 0.6 0.6 ZnO 80 3.8 3.8 3.8 3.8 TBBS 2.0 2.0 2.0 2.0 TBTD 80 0.4 0.4 0.4 0.4 sulfur 2.3 2.3 2.3 2.3

e-SBR + micronized powder: styrene-butadiene rubber containing micronized recycled rubber powder obtained as reported above in Examples 1 and 2;

Europrene® 1739 (e-SBR): oil-extended styrene-butadiene rubber (TDAE-oil) obtained from emulsion (Versalis);

ELT: rubber powder B.0/0.35 (d ₉₀ < 0.35 mm) - Albatros;

N220: carbon black;

Aromatic Oils: TDAE ("Treated Distilled Aromatic Extract") - NORMAN 346 - ORGKHIM;

WB 220 (processing aid): Struktol;

Stearic acid: Sigma Aldrich;

TMQ (antioxidant): polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (Nord Chemie);

Rhenogran® ZnO 80 (Activator): Zinc Oxide (Lanxess);

TBBS (accelerator): N-tert-butyl-2-benzothiazylsulfenamide, Vulkacit® NZ/EGC (Lanxess);

TBTD 80 (accelerator): tetrabutylthiourame disulfide (Sigma Aldrich).

Table 6 below shows the physical-mechanical properties of the vulcanized compounds obtained and the corresponding measurement methods.

Property compound Justice unit of measure standard method (A) (B) (C) (D) Mooney Viscosity
(Mooney viscosity) (MU) ASTM D1646
(2018) 62.2 74.5 62.8 65.9 stress at break (MPa) ASTM D412C (2016) 16.8 16.5 16.4 15.9 elongation at break (%) ASTM D412C (2016) 501 479 475 467 Hardness (shore A) ASTM D2240 (2015) 60 60 59 60 tear resistance (N/mm) DELFT ISO34 (2015) 33.4 35.2 32.5 33.3 Abraded volume (mm ³ /40m) ASTM D5963 (2019) 125 123 136 139

From the data reported in Table 6, the compounds [Compound (A) and Compound (B)] containing styrene-butadiene rubber containing micronized recycled rubber powder obtained according to the method of the present invention, obtained by dry mixing, It is clear that the physico-mechanical properties are maintained or even improved compared to compounds comprising styrene-butadiene rubber and recycled rubber powder [Compound (C) and Compound (D)]. In particular, it should be noted that compounds (A) and (B) show improvements with respect to tear resistance and wear volume compared to compounds (C) and (D), respectively.

Example 6

The physical-mechanical properties of compound (B) were tested using styrene-butadiene rubber SBR containing micronized recycled rubber powder + 20 with a particle size ranging from 0.8 mm to 2.5 mm (Tritogran 1 - P - 0.8-2.5 mm - - Tritogom). The physico-mechanical properties of compound (E) containing the ELT of phr were compared, and the rubber was obtained by operating as described in Example 1.

Compound (E) had the same components and amounts reported in Table 5 for compound (B) (i.e., 157.5 phr of e-SBR + obtained by operating under micronized recycled rubber powder + the above additional components of the same phr).

Table 7 below shows the properties and relative measurement methods of the obtained vulcanized compounds.

Property compound Justice unit of measure method (B) (E) Mooney Viscosity (MU) ASTM D1646
(2018) 74.5 65.4 stress at break (MPa) ASTM D412C (2016) 16.5 12.3 elongation at break (%) ASTM D412C (2016) 479 434 Hardness (Shore A) ASTM D2240 (2015) 60 58 tear resistance (N/mm) DELFT ISO34 (2015) 35.2 34.9 wear volume (mm ³ /40m) ASTM D5963 (2019) 123 128

From the data reported in Table 7, it can be seen that the compound [Compound (B)] comprising styrene-butadiene rubber containing the micronized recycled rubber powder obtained according to the method of the present invention is styrene-butadiene rubber and recycled rubber having a larger particle size. It is clear that it has improved physico-mechanical properties compared to the compound containing rubber powder [compound (E)].

Claims (15)

A method for producing styrene-butadiene rubber containing micronized recycled rubber powder, the method comprising:
(a) preparing a suspension comprising micronized recycled rubber powder, water and at least one surfactant;
(b) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex to obtain a styrene-butadiene latex containing micronized recycled rubber powder;
(c) adding the latex obtained in step (b) to coagulation to obtain coagulated styrene-butadiene rubber containing micronized recycled rubber powder;
includes;
here:
- in step (a), the particle size of the micronized recycled rubber powder is in the range of 0.05 mm to 0.8 mm, preferably in the range of 0.1 mm to 0.4 mm;
- In step (a), the at least one surfactant is present in an amount ranging from 0.5% to 3% by weight, preferably from 1% to 2.5% by weight, based on the total weight of the micronized recycled rubber powder. do;
- in step (a), the micronized recycled rubber powder has a concentration in water ranging from 1% to 50% by weight, preferably from 5% to 30% by weight, relative to the total weight of the water. The method of claim 1, wherein in step (a), the at least one surfactant is selected from:
- nonionic surfactants such as polyoxyethylene derivatives of fatty acids, alkyl-polyglucosides, ethanolamides, ethoxylated amides, ethoxylated amines, ethoxylated acids, polyoxyethylene alkyl-ethers or mixtures thereof; and/or
-anionic surfactants such as salts formed by long chains of carbon atoms terminated with carboxylate or sulfonate groups [eg sodium lauryl sulfate (SLS), sodium lauryl ethoxy sulfate (SLES)], alkyl-benzene- sulfonic acids (ABS), polysulfonic acid aromatic ethers or mixtures thereof; Sodium, potassium, lithium of saturated or unsaturated fatty acids containing 6 to 22 carbon atoms in the molecule, such as caproic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid or mixtures thereof or an ammonium salt, preferably sodium or potassium, or a mixture of said salts; Dimerization, disproportionation of resinous acid mixtures containing abietic acid, neoabietic acid, palustric acid, levopimaric acid or mixtures thereof; sodium, potassium, lithium or ammonium salts, preferably sodium or potassium, of modified resin acids obtained by hydrogenation, modification, or mixtures of said salts; and/or
- cationic surfactants such as long chain quaternary ammonium salts [eg benzalkonium chloride (BAC), cetyl-trimethylammonium bromide (CTAB), hexadecyltrimethylammonium bromide] or mixtures thereof; and/or
- amphoteric surfactants such as coco-amidopropyl-betaine, dodecyl-betaine, lecithin, aminocarboxylic acids or mixtures thereof. 3. The method according to claim 1 or 2, wherein step (a) is carried out for a variable time depending on the size of the mixer and sufficient to obtain a homogeneous suspension, preferably in the range of 5 to 60 minutes, preferably in the range of 10 to 60 minutes. A method for producing styrene-butadiene rubber comprising micronized recycled rubber powder, carried out at a temperature in the range of 20 ° C to 90 ° C, preferably in the range of 50 ° C to 80 ° C for a time in the range of 40 minutes. 4. The method according to any one of claims 1 to 3, wherein in step (b), the at least one styrene-butadiene latex is in the range of 10% to 50% by weight, preferably 15% by weight relative to the total weight of the latex. with an amount of styrene-butadiene polymer ranging from 10% to 60% by weight, preferably from 20% to 50% by weight, relative to the total weight of the latex. , Method for producing styrene-butadiene rubber containing micronized recycled rubber powder. The method according to any one of claims 1 to 4, wherein in the step (b), the suspension obtained in the step (a) is 5% to 5% by weight based on the total weight of the styrene-butadiene rubber contained in the latex. A method for producing a styrene-butadiene rubber comprising micronized recycled rubber powder, added in an amount such that the amount of micronized recycled rubber powder is in the range of 95% by weight, preferably 8% by weight to 35% by weight. 6. The method according to any one of claims 1 to 5, wherein step (b) is carried out at 20° C. to 20° C. It is carried out at a temperature in the range of 90 ° C, preferably in the range of 50 ° C to 80 ° C, and the micronized recycled rubber powder is, preferably for a period of 1 minute to 45 minutes, preferably in the range of 5 minutes to 15 minutes, the styrene - A method for producing styrene-butadiene rubber comprising micronized recycled rubber powder homogeneously distributed in butadiene latex. A method for producing styrene-butadiene rubber containing micronized recycled rubber powder, the method comprising:
(a1) preparing a suspension comprising micronized recycled rubber powder, water and at least one surfactant;
(c1) mixing the suspension obtained in step (a) with at least one styrene-butadiene latex and subjecting the whole to coagulation to obtain a coagulated styrene-butadiene rubber containing micronized recycled rubber powder;
includes;
here:
- in step (a1), the particle size of the micronized recycled rubber powder is in the range of 0.05 mm to 0.8 mm, preferably in the range of 0.1 mm to 0.4 mm;
- In step (a1), the at least one surfactant is present in an amount ranging from 0.5% to 3% by weight, preferably from 1% to 2.5% by weight, based on the total weight of the micronized recycled rubber powder. do;
- in the step (a1), the micronized recycled rubber powder has a concentration in water ranging from 1% to 50% by weight, preferably from 5% to 30% by weight, relative to the total weight of the water. . The method according to claim 7, wherein step (a1) is performed according to claim 2 or claim 3. The micronized recycled rubber powder according to any one of claims 1 to 8, wherein step (c) and step (c1) are carried out in the presence of at least one coagulant selected from alkylamine-epicloridine copolymers. Method for producing a styrene-butadiene rubber comprising a. 10. The method according to any one of claims 1 to 9, wherein step (c) and step (c1) depend on the size of the coagulation mixer, the amount of suspension obtained in step (a) or step (a1) and the styrene used - in the range of 40 ° C to 90 ° C for a time variable depending on the amount of butadiene latex, temperature and pH, the stirring system used, preferably in the range of 5 minutes to 120 minutes, preferably in the range of 10 minutes to 60 minutes, A method for producing styrene-butadiene rubber comprising micronized recycled rubber powder, preferably carried out at a temperature in the range of 60 ° C to 80 ° C. 11. The method according to any one of claims 1 to 10, wherein step (c) and step (c1) are carried out at a pH of 5 or less, preferably in the range of 2.5 to 4, comprising micronized recycled rubber powder. Method for producing styrene-butadiene rubber. 12. The method according to any one of claims 1 to 11, wherein in step (c) and step (c1) at least one inorganic acid such as sulfuric acid or phosphoric acid is added, preferably sulfuric acid, and at least one organic acid is A process for producing styrene-butadiene rubber comprising micronized recycled rubber powder, added in an amount to maintain the pH at 5 or less, preferably in the range of 2.5 to 4, during the entire period of steps (c) and (c1). 13. The method according to any one of claims 1 to 12, wherein the production process is carried out in batch or continuously, preferably continuously, of styrene-butadiene rubber comprising micronized recycled rubber powder. manufacturing method. A vulcanizable elastomer composition comprising at least one filler selected from at least one styrene-butadiene rubber, carbon black, silica or mixtures thereof comprising micronized recycled rubber powder obtained according to any one of claims 1 to 13 and at least one vulcanizing agent. A vulcanized product obtained from vulcanization of a vulcanizable elastomer composition according to claim 14 .

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